1. Field of the Invention
This invention relates to a triggering device for a vehicle occupant safety apparatus such as an air-bag apparatus or a vehicle safety-belt pretensioner (tightener).
2. Description of the Related Art
U.S. Pat. No. 5,107,245 discloses a control arrangement for the occupant restraint system of an automotive vehicle which includes an acceleration pickup for sensing deceleration of the vehicle and providing an acceleration signal. A trip device is in the occupant restraint system. A microcomputer processes the acceleration signal. The microcomputer supplies one or more trip signals to the trip device when the result of processing of the acceleration signal fulfills a criterion for activation of the occupant restraint system. A monitoring circuit external to the microcomputer includes an associated stable oscillator providing a reference signal. The monitoring circuit serves to monitor, as to correct frequency by comparison with the reference signal, a check signal derived from a clock signal of the microcomputer. The monitoring circuit produces an enable signal when the check signal has the correct frequency. The monitoring circuit activates an indicating means when the check signal is found to be incorrect. The monitoring circuit prevents the supply of the trip signal to the trip device in response to the disappearance of the enable signal.
U.S. Pat. No. 5,359,515 corresponding to Japanese published PCT application 4-506495 discloses a vehicle occupant safety system which includes a sensor device having at least two sensors, and a processing device having at least two processing circuits for the respective sensor signals. The vehicle occupant safety system in U.S. Pat. No. 5,359,515 further includes a computing system and a trigger circuit each having at least two stages for a safety device. For providing a high degree of safety with relatively low costs, the computing system is constructed as a single-computer system in such a way that it processes the data of the two processing circuits in two programs with staggered timing with respect to one another.
Japanese published unexamined patent application 5-69791 discloses a side-crash sensing system for automotive side air-bag devices in which an air-bag trigger component is controlled in response to the output signals of plural acceleration sensors.
Japanese published unexamined patent application 5-38998 discloses an arrangement of acceleration sensors for an automotive air-bag device. Specifically, in the sensor arrangement of Japanese application 5-38998, a crash sensor is located at a center of a front of a vehicle body outside a passenger compartment, and two crash sensors are located near front-right and front-left vehicle wheels respectively. The former crash sensor is referred to as the central crash sensor while the latter crash sensors are called the side crash sensors. As viewed from above, the three crash sensors extend at the comers of an isosceles triangle respectively. In addition, a safety sensor is disposed in the passenger compartment within the vehicle body. The three crash sensors are electrically connected in parallel. The safety sensor is electrically connected in series with the parallel combination of the crash sensors. When the safety sensor and at least one of the crash sensors simultaneously fall into ON states, the air-bag device is triggered and activated. A frontal collision can be quickly detected by the central crash sensor. Offset collisions can be detected by the side crash sensors. Collisions against front pillars of the vehicle body can also be detected by the side crash sensors.
U.S. Pat. No. 5,072,966 corresponding to Japanese published unexamined patent application 3-273959 discloses an energy absorbing structure for a vehicle body side portion which includes a pair of vehicle body members constituting two side portions of a vehicle body, and a pair of collision detection sensors for respectively detecting collisions on two side surfaces of the vehicle body. In addition, one air bag is provided in each vehicle body member. Each air bag can be unfolded toward the interior of a passenger room, and can receive at least one passenger who is moved sideways by a side collision. In the energy absorbing structure of U.S. Pat. No. 5,072,966, a timing varying unit serves to change the unfolding timings of the two air bags in accordance with a side-collision direction on the basis of detection results from the collision detection sensors. The air bags are unfolded in accordance with the unfolding timings set by the timing varying unit.
Japanese published unexamined patent application 5-270355 discloses an arrangement of G sensors for a flat floor vehicle which detects not only longitudinal gravity but also a yaw rate through easy computation without disturbing free walking of occupants in a vehicle room. In the arrangement disclosed by Japanese application 5-270355, right and left G sensors are located at laterally symmetrical positions about the central longitudinal line of a vehicle body on which the center of gravity of the vehicle is present. Both the G sensors are on a vehicle floor panel outside a walk-through region. The right G sensor extends below a right front seat while the left G sensor extends below a left front seat.
Japanese published unexamined utility model application 6-79667 discloses an air-bag apparatus for an automotive vehicle which includes a sensor for detecting a shock from the front, and two sensors for detecting shocks in transverse directions. These sensors are located in a front portion of a vehicle body. Air bags respond to the output signals of the sensors. The air bags are located in front and at side of a driver's seat and a passenger's seat respectively.